74 



b. Body somewhat leporiform, with the hind limbs much longer than 

 the fore, (as in the Leporids.) Teeth comparatively differentiated. 



DICHOBUNIDAE. (XXXIX.) 



II. Molars (M) attypically tuberculiferous. Canines of lower jaw enlarged 

 and often developed as tusks, entirely differentiated and distant from 

 incisors. Palatine bones scarcely contracted behind, thick, and (at the 

 walls of the posterior nares) articulated with the terminal portion of the 

 supramaxillary bones. Digestive system not adapted for rumination : 

 stomach imperfectly septate. — Axis with the odontoid process conical. 

 (Flower.) — (Omnivora.) 



A. Body massive, with the feet phalangigrade, and their external (2, 5) 

 toes well developed and produced as far as or beyond the first phalanges 

 of the middle (3 — 4) toes ; the last phalanges wide and with convex 

 margins : manus with unciform bone much broader than high, and with 

 second phalanx wedged between trapezoid and magnum ; pes with 

 cuboid broader than high. Lower jaw with a deep preangular expansion 

 directed forwards. (Snout rounded and with the nostrils open upwards 

 and sideways. Mammae two, inguinal.) Obesa. 



f Molars of upper jaw with a bow-shaped (convex extrorsely) longitudinal 

 and a straight transverse valley dividing four tubercles, all of which are 

 convex introrsely (towards the palate) and concave externally, (thus 

 simulating the teeth of ruminants.) Molars of lower jaw narrower than 

 those of upper, and with the longitudinal valley very narrow : (last 

 molar with a supplementary. posterior lobe.) Canines comparatively 

 small and cylindro-conic. (Merycopotamoidea.) 



MERYCOPOTAMLDAE. (XL.) 



! Molars (M) of upper jaw with nearly straight or irregularly sinuous 

 longitudinal and transverse valleys dividing four tubercles, of which 

 the external two are convex extrorsely and the inner two convex in- 

 trorsely (towards the palate.) Molars of lower jaw resembling those 

 of upper, (the last molar with a supplementary posterior lobe.) 

 Canines very large and furrowed along their posterior surface. (Hip- 

 popotamoidea.) 



HIPPOPOTAMIDAE. (XLI.) 



B. Body suiform ; with the feet unguligrade, and their external toes re- 

 duced in size and not produced or assisting in progression ; the last 

 phalanges elongated and trihedral: manus with the unciform little or 

 no broader than deep, and with the second phalanx not wedged be- 

 tween the trapezoid and magnum ; pes with cuboid deeper than broad 

 and emarginated behind. Lower jaw with.no preangular expansion. 

 (Snout disciform and with the nostrils in it and open forwards. Mam- 

 mae in increased number (4 to 10), ventral as well as inguinal.) Seti- 

 fera. 



1. True molars of upper jaw with oblong crowns with four or more 

 principal sub-conical lobes and accessory smaller ones. 



